Originally Posted by
InsaneDavid
Modding a Genesis 2 requires you trace a couple of pins from the 315-XXXX chip and isolate them. Pin 107 of this chip runs to a +5v plain for US and a GND plain for JPN. Basically you want to find where it meets up with the +5v plain and isolate it by cutting around it until it is isolated - don't just cut the trace as there's a VIA you can pick up the connection from that you want to leave in tact. Then you solder the center of a SPDT to the VIA or connecting point that runs to pin 107 of the 315-XXXX chip. One of the other pins on the switch gets connected to +5v (I usually get it from any connection found that meets up with A26 / B26 of the expansion port as that's +5v) for US mode, and the other pin goes to GND (again, A12, B12, A30 and B30 of the expansion port are GND but GNDs are easy to find) for JPN mode. 50Hz (PAL) / 60Hz (NTSC) is controlled by the same chip except pin 46 instead - GND for 50Hz and +5v for 60Hz. Procedure is pretty much the same. Sounds more complicated but I like modding Genesis 2 systems more. Remember if you're modding PAL Mega Drive systems you REALLY need to put in a 50Hz / 60Hz switch - world of difference.